From mboxrd@z Thu Jan  1 00:00:00 1970
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Date: Fri, 12 Oct 2007 16:26:42 +0200
From: "CHABAL David" <david.chabal@domain.hid>
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Subject: Re: [Xenomai-help] awful latencies (~110us)
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To: Jan Kiszka <jan.kiszka@domain.hid>
Cc: xenomai@xenomai.org

Jan Kiszka a =E9crit :
> CHABAL David wrote:
>> Philippe Gerum a =E9crit :
>>> I suspect the tracer to induce massive cache misses on your setup, wh=
ich
>>> limits the interpretation we can have of this log. Could you apply th=
e
>>> following patch, and post back the frozen log for the very same test?
>>> TIA,
>>>
>>> --- 2.6.20-ipipe-1.8-08/kernel/ipipe/core.c~    2007-09-16
>>> 16:54:34.000000000 +0200
>>> +++ 2.6.20-ipipe-1.8-08/kernel/ipipe/core.c    2007-10-10
>>> 13:05:28.000000000 +0200
>>> @@ -283,7 +283,7 @@
>>>      unsigned long flags;
>>>      int s;
>>> =20
>>> -    local_irq_save_hw(flags);
>>> +    local_irq_save_hw_notrace(flags);
>>>      __raw_spin_lock(lock);
>>>      ipipe_load_cpuid();
>>>      ipd =3D per_cpu(ipipe_percpu_domain, cpuid);
>>> @@ -302,7 +302,7 @@
>>>      ipd =3D per_cpu(ipipe_percpu_domain, cpuid);
>>>      if (!raw_demangle_irq_bits(&x))
>>>          __clear_bit(IPIPE_STALL_FLAG, &ipd->cpudata[cpuid].status);
>>> -    local_irq_restore_hw(x);
>>> +    local_irq_restore_hw_notrace(x);
>>>  }
>>> =20
>>>  /*
>>>
>> The freeze file enclosed is generated with this patch and the i8259.c
>> patch.
>>
>> ---|------------|------------|------------|--------|------------------=
-------
>>
>> RTS|       5.570|       9.400|      85.356|       0|    00:08:55/00:08=
:55
>>
>> Should I try without the I-pipe debugger ?
>=20
> Never say never, but the tracer most probably not causing these
> latencies. Currently, all points to the good-old programmable interrupt
> controller.
>=20
> Do you have CONFIG_X86_UP_IOAPIC enabled? If no, please try to do so.
>=20
> Jan
>=20
Yes, I did it.